1217-49-8Relevant academic research and scientific papers
Palladium-Catalyzed, Copper(I)-Promoted Methoxycarbonylation of Arylboronic Acids with O-Methyl S-Aryl Thiocarbonates
Cao, Ya-Fang,Li, Ling-Jun,Liu, Min,Xu, Hui,Dai, Hui-Xiong
, p. 4475 - 4481 (2020/04/10)
Here, we report O-methyl S-aryl thiocarbonates as a versatile esterification reagent for palladium-catalyzed methoxycarbonylation of arylboronic acid in the presence of copper(I) thiophene-2-carboxylate (CuTC). The reaction condition is mild, and a variety of substituents including sensitive-Cl,-Br, and free-NH2 could be tolerated. Further applications in the late-stage esterification of some pharmaceutical drugs demonstrate the broad utility of this method.
Extended Study of Visible-Light-Induced Photocatalytic [4 + 2] Benzannulation: Synthesis of Polycyclic (Hetero)Aromatics
Chatterjee, Tanmay,Lee, Da Seul,Cho, Eun Jin
, p. 4369 - 4378 (2017/04/28)
Herein we report an extended study of [4 + 2] benzannulation reactions of 2-(hetero)aryl-substituted anilines with alkynes by visible light photocatalysis. The method requires the use of tBuONO as a diazotizing agent and 0.3 mol % of fac-Ir(ppy)3 as a photocatalyst at room temperature. The reaction proceeded in a chemo- and regioselective manner with high functional group tolerance under mild conditions allowing the preparation of a wide variety of polycyclic (hetero)aromatic compounds, including phenanthrenes, in moderate to high yields. This procedure is amenable to gram-scale synthesis of 9-phenylphenanthrene.
Sandmeyer reactions. Part 6. A mechanistic investigation into the reduction and ligand transfer steps of Sandmeyer cyanation
Hanson, Peter,Rowell, Simon C.,Taylor, Alec B.,Walton, Paul H.,Timms, Allan W.
, p. 1126 - 1134 (2007/10/03)
For Sandmeyer cyanation at 298 K in 50% v/v aqueous acetonitrile buffered at pH 8, absolute rate constants have been obtained for the reduction of 4-methoxybenzenediazonium tetrafluoroborate by the cyanocuprate(I) anions Cu1(CN)43-, Cu1(NCMe)(CN)32- and Cu1(NCMe)2(CN)2- as (0.50 ± 0.05), (0.12 ± 0.03) and 0.0 dm3 mol-1 s-1, respectively. The relative reactivity of the two reactive cyanocuprates reflects the estimated difference in their standard reduction potentials. Ligand transfer to the aryl radical from the cyanocuprate(II) anions produced in the reaction occurs within the solvent cage. By use of radical clocks, first order rate constants of the order of 1 × 108 s-1 for ligand transfer between the caged reactants can be evaluated although the transfer rate may vary from one aryl radical to another. No difference was discerned in ligand transferring reactivity between the two cyanocuprate(II) complexes involved.
Sandmeyer reactions. Part 4. An investigation into the cyclisation modes of Pschorr phenanthrene synthesis
Hanson, Peter,Loevenich, P. Wilfried,Rowell, Simon C.,Walton, Paul H.,Timms, Allan W.
, p. 49 - 64 (2007/10/03)
Comparison of the cyclisation regiochemistries in the heterolysis and the copper-catalysed homolysis of methyl (E)-3-(2-diazoniophenyl)-2-(3-halophenyl)propenoate tetrafluoroborates indicates that the homolytic pathway involves direct closure of the six-membered ring and not a five-membered ring closure followed by ring expansion. From competition experiments in which homolytic cyclisation of the corresponding non-halogenated compound was run against hydrogen abstraction from hypophosphorous acid, a cyclisation rate constant kC = (3.0 +/- 0.5) x 109 s-1 at ambient temperature was estimated which, when used in conjunction with a literature value for the homolytic phenylation of benzene, allows evaluation of a statistically corrected effective molarity of 2 x 104 mol dm-3 for homolytic Pschorr phenanthrene closure. Regioselectivity considerations imply that, by contrast, heterolytic Pschorr phenanthrene closure exhibits unit effective molarity. A mechanistic rationale is presented to explain these patterns of behaviour.
Synthesis and Photochemistry of 5,7-Bis(diazo)-1,2,3,4-dibenzocyclohepta-1,3-dien-6-one. Generation and Reactions of Phenanthrenodiazacyclopentadiene, Phenanthrenocyclopropenone, and 9,10-Phenanthryne
Tomioka, Hideo,Okuno, Akemi,Sugiyama, Takehiko,Murata, Shigeru
, p. 2344 - 2352 (2007/10/02)
The title compound 15 was prepared as the first 1,3-bis(diazo) ketone incorporated into a seven-membered ring, and its photochemical pathways were investigated not only by product analysis study but also by using matrix isolation spectroscopy.Irradiation of 15 in alcoholic solvents gave 9-(alkoxycarbonyl)phenanthrene 16 as a main product, while similar irradiation in non-nucleophilic solvents provided diphenanthreno-syn-1,5-diazabicyclooctadienedione (20).The formation of these products is interpreted as indicating that 15 eliminates one of two diazo functions upon photoexcitation to form 9-diazo-10-carbonylphenanthrene (21) which either reacts with alcohol by eliminating the second dinitrogen, leading to 16, or undergoes dimerization to form 20.Photolysis of 15 in an ethanol matrix at 77 K gave 9-ethoxyphenanthrene (31) as a new product along with 16.Irradiation of 15, matrix-isolated in Ar at 10 K monitored by IR, indicated that phenanthrenocyclopropenone (28) was formed as an initial product which then underwent photodecarbonylation to leave 9,10-phenanthryne (32), and that 32 reacted with CO to reproduce 28 upon photoexcitation.The cyclopropenone (28) was shown to be generated also by photolysis of 9,10-dicarboxyphenanthrene anhydride (33) in Ar matrix at 10 K.A plausible mechanism to explain the observed sequential decomposition of the two diazo functions in the room temperature photolytic run and the formal simultaneous elimination of two dinitrogens in the low temperature matrix run is proposed.
